Electric furnace



A. WESTERBERG.

ELECTRIC FURNACE.

APPLICATION FILED NOV. 1?, 1915.

1,412,764. Patented Apr. 11, 1922.

UNITED" sTAT T allwhom it may concern:

Be it known that I, Anvil) WESTERBERG, a citizen of the Kingdom resident of Djursholm', Stockholm lan,

Sweden, have invented certain new and useful Improvements on Electric Furnaces,

of which the following is a specification.

My invention relates to electric furnaces, which are being operated by means of electric currents from a power source which doeS not permit heavy fluctuations in the load.

Insuch case some kind of resistance is as in order to lessen the Variations in the powersupplies.

Said resistances should preferably be adjustable and inductive rather than of the non-inductive kind in order to economize with the supplyof energy.

Such resistances or choking c'oils,,wh ich consist of a certain-number of turns of copper around iron core,'oifer, as usually made, certain disadvantages. When only some of the turns of the winding are carrying an alternating current, an electromotive force is generated also in the other turns, which complicates in a certain way mechanism necessary for choking powder of the coil.

The present invention has for its object to obviate the beforesaid difficulty by arranging the choking coils as illustrated in the diagrammatic view of the drawing, which accompanies the specification.

Choking coils indicated by 1 on an iron core 2 provided with three legs a, b, and c; The middle one of these. I), is left without winding. one of the outside legs a is wound with twice as many turns as the other outside leg 0. It is, however, clear that the proportion of the number of turns on a. and 0 may be changedas desired.

The magnetic field excited by the winding on one of the outside legs may pass through the path offered therefor by the central leg of the iron core; for this reason the other outside winding may be shortcircuited without inconvenience.

adjusting the tained by shortcircuiting one or the other or both of the outside windings, which may be done by means of only two circuit breakers 3 and 4. One of said circuit breakers may be equipped with an overload release 5' arrangement. 7

of Sweden and choking coils. be shortclrcuited independently of the other a rule employed in series with the furnace the switching are arranged Adjustment in three steps may be ob-v ES PATENT ornce.

ARVID wns'rnmanne, or naunsnoLm, swarm.-

ammo FURNACE.

speclfic f L p at10110 ettersla'tent I I. 9 c

Applica tlon N 0 ember 1:, Se! 13.]- N 0. i

If an overload occurs in the furnace this circuit breaker automatically introduces a corresponding reactance in the circuit. limitmg the overload without breaking the current in the furnace. i

If more than 3 regulating steps are necessary more than 2 legs may be provided with Each one of said coils may 0011s by providing one or more legs without w1nd1ngs, which act as one or more magnetlc shunts as described above. The draw-.

mg illustrates a transformer having a pri-v mary wlnding 5 and a secondary winding 6 delivering current to a pair of electrodes 7. The invention is not limited to any'certam method of arranging the electrodes of an electric furnace, but may be usefully em- 'ployed in connection with any kind of electric furnaces. Of course. the same results. wh ch are obtalned by the choking coil descrlbed above, may be obtained by using two or several ordinary choking coils of known construction, but this method will be more expensive and W111 take up more space.

1 Having now clearly described my inven tion I hereby claim and desire to secure by Letters Patents of the United States of 1 America:

1. In an electric'furnace the combination of a plurality of choking coils in series with the furnace all the coils being arranged on one iron core provided with a magnetic shunt without windings.

2. In an electric furnace the combination of a plurality of choking coils in series with the furnace, all the coils being arranged on one lron core provided with a magnetic shunt without windings, the number of turnsin each coil being different from the number of turns of the other coils.

3. In an electric furnace the combination the furnace all the coils being arranged on .one iron core provided with a magnetic shunt of a plurality of choking coils in series with 

